Refrigeration



INVENTQR Curtis C. 00ans William l Killa ffy llll

May 5,V 1942.

F592 I f9.3

Patented May 5, 1942 REFRIGERATION Curtis C. Coons,

North Canton, and William H.

Kitto, Canton, Ohio, assignors to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application October 10, 1938, SerialNo. 234,165

14 Claims.

This invention relates to the art of absorption refrigeration and more particularly to a novel evaporator construction for such system.

While it is possible to drag or sweep the liquid refrigerant through the evaporator from the lowest to the highest points thereof, it is not always desirable to do so. It may be desirable to use evaporator conduits of such diameter that the inert gas stream will not flow therethrough with a velocity high enough to drag or sweep the liquid refrigerant along therewith; the height of the evaporator may be so great that the gas circulating through the evaporator-absorber system is not placed under suicient pressure to rlift the liquid refrigerant entirely through the evaporator; the inert gas may be too light to elevate the liquid through the full height of the evaporator; and with some systems it may be desirable to extend the evaporator below the condenser and to connect the two by a short direct connection.

In the copending application of Curtis C. Coons and William H. Ktto, nled July 20th, 1938, Serial No. 220,188, now Patent No. 2,255,415, issued September 9, 1941, there is disclosed an absorption refrigerating system including'an evaporator of the type in which liquid refrigerant is supplied from the condenser to an intermediate portion of the evaporator, is conveyed therethrough to the upper portion of `the evaporator by a propelled stream of dense inert gas and is then drained from the upper to the lower portions of the evaporator where the unevaporated portion of the refrigerant is then carried through the lowest stage of the evaporator by the inert gas as it is evaporating thereinto to produce useful refrigeration. This evaporator, while functionally operative, has the disadvantage that it requires a complicated and expensive inter drain system to prevent inert gas from by-passing directly into the liquid drain from the lowest to the highest portions of the refrigerator and also to insure that this drain will be blocked to inert gas flow in order to permit liquid refrigerant to ow downwardly therethrough to the lowest por tion of the evaporator.

Accordingly, it is an object of the present invention to provide an absorption refrigerating system of the above referred to type including an evaporator having a drain system interconnecting the gas inlet and outlet portions thereof which will have a high resistance to gas ilow without interposing any material resistance to ow of liquid therethrough whereby such drain will automatically prevent undesirable by-passing of inert gas when the evaporator isv placed in operation, will quickly seal and will allow free flow of refrigerant liquid downwardly therethrough.

vIt is a'further object of this invention tolprof terconnecting the vide an absorption refrigerating system of the type including an evaporator in which the liquid refrigerant is propelled therethrough by an inert gas stream in which there is` provided a drain ingas inlet and outlet portions of the evaporator including obstructing balles therein or shaped to produce obstructions to gas ow `which do not materially impede liquid ilow through such drain.

It is a further object of the present invention to provide an evaporator 0f the type having a liquid drain between the gas inlet and outlet portions thereof with a drain construction which will insure initial starting of the apparatus and `will thereafter continuously maintain a body of liquid in the drain suflicient to prevent gas from luy-passing therethrough and to insure prompt re-starting ofthe apparatus in response to appropriate `temperature conditions.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic illustration of an absorption vrefrigerating system embodying the invention in which the evaporator is shown on an enlarged scale and in perspective.

Figure 2' isa cross-sectional detail on an enlarged scale of a portion of the apparatus illustrated in Figure 1.

Figure 3 is a cross-sectional detail illustrating a modied form of the invention.

Figure 4 is a further cross-sectional detail illustrating another modied form of the invention.

Referring now to Figure 1 in detail, there is disclosed a continuous absorption refrigerating system of the three-fluid type embodying a boiler B, an analyzer D, a rectifier R, a condenser C, an evaporator E, a gas heat exchanger G, a liquid heat exchanger L, an absorber A, a solution reservoir S, and a circulating fan F which is driven by an electrical motor M. These elements are suitably connected together by various conduits to form a plurality of gas and liquid circuits, to which reference will be made in more detail hereinafter, constituting a complete refrigerating system.

The above described refrigerating system will be charged in any suitable manner with a refrigerant, such as ammonia, an absorbenu'such as water, and an inert pressure equalizing medium, preferably a dense inert gas such as nitrogen.

The 'boiler B may be heated in any desired manner as by an electrical cartridge heater or by a combustible fuel burner.

The circulating motor M and the heater for the boiler B will also be controlled in any desired `manner.l A preferredvcontrol mechanism is disclosed in the copending application of Curtis C. Ccons, Serial No. 143,424, filed June 16th, 1937, now Patent No. 2,228,343, issued January 14, 12941.

The application of heat to the boiler B generates refrigerant vapor from the strong solution normally contained therein. The refrigerant vapor so generated passes upwardly through the analyzer D in counterflow to` strong solution iiowing downwardly therethrough.V In the analyzer, vapor of absorption solution generated in the boiler is condensed by contact with the strong solution and the heat of condensation serves to generate further refrigerant vapor which then passes through the conduit il to the upper portion of a tubular air-cooled condenser C. The conduit Il includes the rectifier R which serves tocause condensation of any vapor of absorption solution whichv may pass through the analyzer D.

The refrigerant vapor discharges into the condenser C which extends to a level appreciably below the level of the top portion of the evaporator E and flows downwardly therethrough as it is being condensed by heat exchange with cooling air flowing over the outer surface of the condenser and the fins attached thereto. The condensate formed in the condenser C is then drained therefrom through a conduit I2 into the evaporator E to which reference will be made in more detail hereinafter.

The weak solution formed in the boiler B by the generation of refrigerant vapor is conveyed therefrom through a conduit i5, the inner path of the liquid heat exchanger L anda conduit it which discharges into the upper end of the tubular air-cooled absorber A. For purposes of convenience, the absorber A has been shown as being vertically positioned herein. However, it may be positioned in any plane from the vertical to a plane inclined slightly to the horizontal. It is apparent that the upper portion of the absorber is at an elevation above the liquid level normally prevailing in the boiler-analyzer system wherefore some means must be provided to elevate the weak: solution thereinto. For this purpose a small bleed conduit l1 is connected between the gas discharge conduit I8 of the circulating fan F and the weak solution conduit it below the liquid level normally prevailing therein, whereby the weak solution is elevated into the absorber by gas lift action. The weak solution flows downwardly through the absorber in counterflow relationship to a rich mixture of pressure equalizing medium and refrigerant vapor which is conveyed thereto in a manner to be described more fully hereinafter. In the absorber the refrigerant vapor content of the mixture is absorbed by the solution which then becomes strong solution and flows to the bottom portion of the absorber where it is drained through a conduit 20 into the :strong solution reservoir S. The heat of absorption generated by the absorption process is rejected to air flowing over the outer walls of the absorber vessel and in contact with the air-cooling fins mounted thereon. The strong solution is conveyed from the reservoir S through the conduit 22, the outer path of the liquid heat exchanger L, and the conduit 23 to the upper portion of the analyzer D.

The lean inert gas discharged by the circulating fan F enters the outer path of the gas heat exchanger G from which it is conveyed through the conduit 25 to the bottom portion of the evaporator E. The evaporator E will be described in detail hereinafter. For the present it is suillcient to state that the propelled stream of inert gas apanage discharging through the conduit 25 circulates upwardly through all portions of the evaporator carrying the liquid refrigerant upwardly therewith as it evaporates into the inert gas stream. The rich mixture formed in the evaporator is discharged therefrom through the conduit 28 into the inner path of the gas heat exchanger G fromV which it is conveyed through the conduit 2d to the bottom portion of the absorber A. The rich mixture passes upwardly through the absorber A in counterflow relationship to the solution iiowing downwardly therethrough by gravity in the manner described herebefore. The lean gas formedin the absorber is conveyed from the upper portion thereof into the suction line of the circulating fan F by a conduit 3D, thus completing the inert gas circuit.

The evaporator per se comprises three horizontal vertically spaced coil sections 34, 35 and 36, respectively. A rearwardly inclined large diameter box-cooling conduit 38 is positioned above the uppermost coil section 36. The coil sections 34 and 35 each comprise a pair of U- shaped conduit elements 39 and 40 having the outer legs thereof serially connected by a rear cross-connecting conduit 4l. The coil section 36 comprises a conduit element 4B corresponding to the conduit elements 40 previously described and a rear cross-connecting conduit 4| corresponding to the conduit elements 4l previously described. However, the conduit element 39 is replaced by an L-shaped conduit element 42 which terminates in a riser conduit 43 opening into the forward end of the box-cooling conduit 38. The inert gas supply conduit 25 opens into the inner leg of the conduit element 40, and the inner leg of the conduit element 39 of the coil section 34 terminates in a riser conduit 4G which communicates with the inner leg of a superposed conduit element 39. The inner leg of the conduit element 4U of the coil section 35 terminates in a riser conduit 41 which communicates with the inner leg of the superposed conduit element 40.

The liquid refrigerant supply conduit l2 opens into the central portion of the cross-connecting conduit 4| of the coil section 35. A drain conduit 50 opens into the top central portion of the coil section 34 adjacent its point of connection with the riser conduit 46 and communicates with the strong solution return conduit 22 below the liquid level normally prevailing therein.

A return drain conduit 60 extends from the rear end of the box-cooling conduit 38 to a point below the coil section 34 and then turns upwardly to join the coil section 34 adjacent its point of connection with the gas inlet conduit 25, thus forming a U-shaped liquid sealing loop extending beneath the coil section 34.

Referring now to Figure 2, a section of the conduit 6i) is shown on an enlarged scale from which it will be seen that the said conduit is partially or completely filled with a material such as steel wool which will offer a high resistance to gas flow through the tube while permitting liquid to ow downwardly therethrough without materially impeding the flow of liquid.

Preferably, the obstructing material 62 does not completely ll the tube 60 but is placed in part only of the vertically extending portion thereof above the U-shaped loop. This serves the purpose of preventing excessive by-passing of the inert gas and leaves the U-shaped loop unobstructed to ll with liquid to form a gas tight liquid seal. tween the gas inlet and outlet portions of the Due to the pressure differential be-l evaporator there will be a pressure balancing liq-l to re-form this column when the apparatus is restarted after initial operation without depressing the liquid in the gas inlet side of the system sufciently to break the liquid seal.

It; will be understood that the refrigerating systern will be encased in a suitable cabinet with the mechanism properly distributed in lower and rear mechanism compartments and with the evap orator projecting into the storage compartment of the cabinet. The evaporator, `of course, will be encased in a suitable housing including shelves resting on the various coil sections 34 and 35 to support ice cube trays.

The evaporator including the conduit 25 may, if desired, be constructed of a single piece of relatively small diameter tubing, on the order of one-half inch inside diameter, for example, or it may be constructed of suitably shaped sections of tubing welded together as may be desired.

The operation of this form of the invention will now be described. diameter of the tubing constituting the evaporator proper, excluding, of course, the large di ameter box-cooling conduit 38, the inert gas will flow through the evaporator at a high velocity as compared with gas velocities previously used in the evaporators of absorption refrigerating systems. The gas discharged into the evaporator coil will sweep or drag the liquid refrigerant through all portions thereof into the box-cooling conduit as it is evaporating into the inert gas stream to produce refrigeration. However, if the drain 60 were open the inert gas would tend to bypass therethrough directly from the conduit 25 to the conduit 28 to such an extent that the gas velocity flowing through the evaporator coil proper would not be suinoient to propel the liquid refrigerant therethrough and the velocity of the gas discharging from the upper end of the conduit 50 would be suflicient to prevent liquid refrigerant from iiowing downwardly into l the bottom coil 34 of the evaporator. It is for this reason that the obstructing material is inserted in the conduit 60.

When the apparatus is initially started there is some by-passing of inert gas through the conduit (50 but the quantity of gas is held to a very small amount by reason of the high resistance to gas flow offered by the obstructing material 62. As a result, the velocity of the gas flow through the evaporator proper is substantially at its proper value and the instant liquid refrigerant discharges through the conduit I2 it is carried through the coil section 35, the riser conduit 47, the coil section 36. the riser conduit 43, into the box-cooling conduit 33. The liquid refrigerant flows through the box-cooling conduit 38 by gravity as gas ows through that conduit relatively very slowly because of its large diameter. Liquid refrigerant reaching the gas discharge end of the box-cooling conduit 38 then iiows downwardly throughthe conduit Eil and eventually seals the bottom U-shaped portion thereof against passage of inert gas therethrough whereby all the gas subsequently is forced to pass directly through the evaporator conduit. The liquid refrigerant discharged into the coil section 34 by the conduit 30 is propelled therethrough by the inert gas ,stream as it is evaporating.

A body of liquid is continuously maintained in 75 Due to the relatively small the Uv-shaped loop portion of the apparatus after initial operation `of thesystem to seal the drain 60 against subsequent by-passing of inert gas. Normally this body of liquid refrigerant will not evaporate during the de-energized portions of the operating cycles of themachine because there will be no flow of inert gas through the evaporator at this time andvbecause of the low temperature prevailing in the evaporator and drain 60.

Though it is preferred to provide the lower U-shaped liquid sealing device, it is not essential to proper operation of the system. If it is not feasible to provide the U-shaped seal below the coil section 34, it may be` eliminated in which event the conduit 60 will join the conduit 25 adjacent its point of connection with the coil section 34. The high gas flow resistance of the conduit 60 will prevent objectionable by-passing of the inert lgas under these circumstances.

It is not denitely known whether refrigeration is produced in the riser conduit 46 and the oonduitsection 39 of the coil section 35 by liquid refrigerant which is carried upwardly thereinto, by liquid refrigerant ycounterlowing to the inert gas stream in the coil section 35, or simply by the relatively cold inert gas stream flowing into those portions of the evaporator; however, refrigeration is substantially uniformly produced in allportions of the evaporator.

The drain 50 functions primarily as an emergency drain, as it is not normally operative for any purpose.. During normal operation of the apparatus there is never Aa sufficient collection of liquid refrigerant in the coil section 34 to raise the level therein to the lowest portion of the drain 50. Any liquid collected therein is either evaporated or swept upwardly into the coil section 35. However, if the apparatus should be up-ended,

for example in shipping and installation, absorption solution might nd its way into the coil section 34 and might even block the same to inert Igas ow were it not for the drain system which is positioned so as to prevent this phenomena but without completely draining 'the coil section 34. After a short period of operation of the refrig erator any liquid such as absorption solution which was trapped in the coil section 34 would be swept through the evaporator and eventually nd its way into the absorption solution circuit. Also, during normal operation the apparatus is preferably controlled intermittently, as a result of which an appreciable quantity of liquid refrigerant will iiow downwardly into the coil section 34 when the circulating fan F is deenergized. With. the arrangement illustrated this liquid simply is stored in the evaporator and awaits reenergization of apparatus to produce refrigerfrigerant would be Wasted. i

Referring now to Figure 3, there is illustrated a modied form of the conduit 60, designated 60', which includes therein a liner 65 provided with a plurality of out-struck tongue elements resistance to ow of gas upwardly therethrough, whereby the apparatus very quicklygoes into operation. The liner 65 need not extend the full length of the conduit 60 and, in any event, it is desirable to leave the U-shaped loop unobstructed.

Referring now to Figure 4, there is illustrated another modification of the invention in which a conduit 30, corresponding to the conduit 60 described in connection with Figure 1, is provided with a plurality of inde'ntations 61 which will offer high resistance to the flow of inert gas upwardly through the conduit 60" without offering material resistance to the now of liquid downwardly through that conduit. This form of the invention also operates in substantially the same manner as the forms of the invention previously described.

Only detail sections of the conduits 60 and 6D have been illustrated as these elements are designed and intended to replace the conduit 60 of Figures 1 and 2 and perform the same functions.

The action of the inert gas on the liquid refrigerant is as-follows: In substantially yhorizontal and slightly inclined conduits the gas stream passes over the surface of a small stream of the liquid which it propels through the conduit by the dragging or frictional action exerted on the liquid by the gas. In rising and steeply inclined conduits the action is somewhat different, the liquid refrigerant collects to some extent and is maintained in a state of continual violent agitation by the continual discharge of inert gas therethrough, which inert gas blows, sweeps or drags a portion of the collected liquid into the next higher evaporator conduit where the gas again propels the liquid in a stream as mentioned above. n

The propelling action of the inert gas is a function of its density, pressure and velocity of flow. In a refrigerating system in which the total pressure ranges between 270 and 400 pounds per square inch, a dense inert gas, like nitrogen, will circulate the liquid refrigerant satisfactorily through an evaporator approximately l" or lll in height constructed of tubing of approximately 1/2" inside diameter with a pressure drop of between 212 and 4 of water between the gasV inlet and outlet lconnections to the evaporator. Of course, these dimensions are all mutually inter-dependent and a variation in any one will require appropriate variation of the others in order to produce proper results. These dimensions are given by way of example only and are not to be construed as limiting in any sense. A more detailed explanation of this phenomena will be found in the copending application of Curtis C. Coons and William H. Kitto, Serial No. 386,395, led April 2, 1941, which is a continuation-in-part of their application 220,189, filed July 20, 1938. A

According to the present invention there is provided a simple evaporator construction which permits a high evaporator to be utilized without increasing the fan size to prohibitive dimensions. Liquid refrigerant discharges into the central portion of the evaporator and unevaporated liquid refrigerant drains from the top to the bottom thereof where it is again brought into the zone of influence of the inert gas stream. The drain is automatically self-sealing in a very simple and H direct manner without necessitating a complex draining structure, and it remains in gas-sealed condition after initial operation of the system.

While the invention has been illustrated and described herein in considerable detail, it is not assises' to be limited thereto but various changes may be made in the construction, arrangement, proportion of parts without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. Refrigerating apparatus comprising an evaporator, means for supplying refrigerant liquid to an intermediate portion of said evaporator, means for propelling a dense inert gas upwar-dly through said evaporator from the bottom to the top thereof to circulate liquid refrigerant therethrough, means including a liquid trapping gas flow preventing part for draining liquid refrigerant from the top portion of said evaporator to a lower portion thereof, and means within said drain constructed and arranged to impede flow of inert gas therethrough prior to lling of said trap with liquid without materially impeding the flow of liquid from the top of said evaporator to the bottom thereof.

2. Refrigerating apparatus comprising an evaporator, means for supplying refrigerant liquid to an intermediate portion of said evaporator, means for propelling a dense inert gas upwardly through said evaporator to circulate liquid refrigerant therethrough, means for draining liquid refrigerant from the top portion of said evaporator to a lower portion thereof, and a body of occulent material in said drain means.

3. Refrigerating apparatus comprising an evaporator, means for supplying refrigerant liquid to an intermediate portion of said evaporator, means for propelling a dense inert gas upwardly through said evaporator to circulate liquid refrigerant therethrough, means for draining liquid refrigerant from the top portion of said evaporator to a lower portion thereof, and means within said drain for impeding flow of inert gas upwardly therethrough comprising a liner tube having a plurality of tongues projecting inwardly thereof.

4. Refrigerating apparatus comprising an evaporator, means for supplying refrigerant liquid to f an intermediate portion of said evaporator, means for propelling a dense inert gas upwardly through said evaporator to circulate liquid refrigerant therethrough, means for draining liquid refrigerant from the top portion of said evaporator to a lower portion thereof, and a plurality of inwardly projecting gas flow obstruction tongue elements formed in said drain means.

5. Refrigerating apparatus comprising an evaporator, means for supplying refrigerant liquid to an intermediate portion of said evaporator, means for propelling a dense inert gas upwardly through said evaporator to circulate liquid refrigerant therethrough, means for draining liquid refrigerant from the top portion of said evaporator to a lower portion thereof, and a liquid trap gas sealing device in said drain means, said drain means including a gas flow obstructing means between said trap and the top portion of said evaporator.

6. Refrigerating apparatus comprising a boiler, a condenser, an absorber, an evaporator, means for conveying refrigerant Vapor from said boiler to said condenser, means for supplying liquid refrigerant from said condenser to the central portion of said evaporator, means interconnecting said evaporator and said absorber to form a pressure equalizing medium circuit, means for propelling a pressure equalizing medium through said circuit, said circuit being arranged to supply pressure equalizing medium under pressure to the lower portion of said evaporator, means for draining liquid refrigerant elevated by said pressure equalizing medium through said evaporator from the gas outlet thereof to the lowest section thereof, and means adapted to restrict the flow of gas through said drain.

'7. A refrigerating system comprising a solution circuit including a boiler and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber, power-driven means for propelling a dense pressure equalizing medium through said pressure equalizing medium circuit, a refrigerant vapor liquefying means connected to said boiler and to an intermediate portion of said evaporator, means including a liquid seal interconnecting the top and bottom portions of said evaporator, the arrangement being such that liquid refrigerant travels upwardly through said evaporator and is then conveyed to the bottom of said evaporator through said means including a liquid seal, and means for impeding flow of gas through said liquid seal prior to sealing thereof with liquid.

8. Refrigerating apparatus comprising an evaporator, means for propelling a pressure equalizing medium upwardly through said evaporator from the bottom to the top thereof, means forsupplying liquid refrigerant to an intermediate portion of said evaporator, a conduit connecting the gas outlet and bottom portions of said evaporator including a U-shaped portion extending below the bottom portion of said evaporator, and gas flow obstructing means in said conduit adapted to restrict the iiow of pressure equalizing medium therethrough prior to filling of said U-shaped portion of said conduit with liquid refrigeran 9. Refrigerating apparatus comprising an upstanding gas and liquid contact element, means for supplying a liquid to an intermediate portion of said element, means for supplying an inert gas under pressure to the lower portion of said element under conditions such that it will flow upwardly therethrough with sufficient force to circulate the liquid upwardly, means for transferring liquid from an upper portion of said element to the bottom portion thereof, and an obstructing device in said transfer means for obstructing the flow of inert gas therethrough without materially impeding the flow of liquid therethrough.

10. An evaporator adapted for use in refrigerating systems of the type utilizing an inert pressure equalizing medium into which a liquid is evaporated to produce a refrigerating effect comprising a plurality of vertically spaced serially connected coil sections, a finned space cooling element serially connected to said coil sections, and means including a liquid seal trap and liquid column pressure balancing forming portion connecting said space cooling element and the lowest of said coil sections, said last mentioned means including means for obstructing gas flow from said lowest coil section to said space cooling element therethrough without materially impeding liquid flow therethrough from said space cooling element to said lowest coil section.

11. Absorption refrigerating apparatus comprising an insert gas circuit including an evaporator and an absorber, a solution circuit including a generator and said absorber, means for liquefying refrigerant vapor connected to receive refrigerant vapor from said generator and to supply refrigerant liquid to an intermediate portion of said evaporator, means in said inert gas circuit for propelling a dense inert gas upwardly through said evaporator to circulate liquid refrigerant therethrough, means for draining liquid refrigerant from the top portion of said evaporator to a lower portion thereof, and means within said drain constructed and arranged to impede flow of inert gas therethrough without materially impeding the flow of liquid from the top of said evaporator to the bottom thereof.

12. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporator and an absorber, a solution circuit including a generator and said absorber, means for liquefying refrigerant vapor connected to receive refrigerant vapor from said generator and to supply refrigerant liquid to an intermediate portion of said evaporator, means in said inert gas circuit for propelling a dense inert gas through said evaporator from the bottom to the top thereof to circulate liquid refrigerant therethrough, and means for draining liquid refrigerant from the top portion of said evaporator to a lower portion thereof, said drain means being constructed and arranged to interpose a high resistance to gas flowing upwardly therethrough and a low resistance to liquid owing downwardly therethrough whereby liquid refrigerant may drain from the top portion of said evaporator to the bottom portion thereof against upwardly iiowing inert gas.

13. Refrigerating apparatus comprising an evaporator, means for supplying refrigerant liquid to said evaporator below the top thereof, means for circulating an inert gas from the bottom to the top of said evaporator under sufficient velocity and pressure to circulate liquid refrigerant through said evaporator by the frictional drag of the inert gas on the liquid refrigerant, and means for conveying unevaporated refrigerant liquid from the upper part of said evaporator to the bottom thereof including a drain conduit constructed and arranged to restrict ow of inert gas without impeding flow of unevaporated liquid refrigerant and to collect a body of said unevaporated liquid refrigerant of suiicient size to block flow of inert gas through said drain conduit.

14. In a refrigerating apparatus of the threefluid absorption type utilizing a liqueable refrigerant, an absorbent for the refrigerant and a gaseous medium which is inert with respect to the refrigerant and absorbent; an evaporator comprising means forming a continuous sinuous passageway having a plurality of vertically spaced substantially horizontal sections; a drain conduit connecting the upper and lower parts of said passageway and including a trap portion arranged to form a gas flow preventing seal, said conduit being constructed and arranged to interpose a high resistance to flow of said gaseous medium without interposing a high resistance to the flow of liquid refrigerant therethrough;

CURTIS C. COONS. WILLIAM H. KITTO. 

